Inflators of the above mentioned kind are known in the art and are disclosed, for instance in the German Utility Model No. 299 05 908 U and in the International Patent Application No. WO95/33389.
Document DE-299 05 908 U describes an inflatable protective jacket for a motorcycle rider provided with an inflator which is automatically operated for inflating the jacket when the motorcycle rider undergoes the impact of a collision. In an inflator of this kind, a blocking device is provided which holds a piercing pin in a cocked condition against the action of a coil compression spring. When the blocking device is released, the piercing pin is driven against and through a scaling plate forming the cap of a gas-containing bottle by action of the thrust exerted by the coil compression spring, thereby causing the gas contained in the bottle to escape therefrom and to flow into the inflatable jacket. The blocking device of the inflator can be automatically released by means of a short operating cord connected at one end to the inflator and at the other end to a motorcycle chassis. The piercing pin of the inflator can be reset in the cocked condition for permitting the inflator to be used again. A first drawback of an inflator of this kind resides in the fact that the piercing pin of the inflator may be retained inside the hole made in the cap of the gas-containing bottle, notwithstanding the thrust exerted by the pressurized gas contained in the bottle, and thereby it may obstruct the flow of the gas into the inflatable jacket. In fact, no measures have been taken until now in order to assure that really the piercing pin of the inflator is drawn out from the hole made in the cap of the bottle in the case the piercing pin is actuated by a coil compression spring. A second drawback of an inflator of this kind resides in the fact that, upon perforation of the sealing plate of the cap of the gas-containing bottle, the piercing pin is contrasted in its backward travel by the coil compression spring, and therefore it obstructs the flow of the gas by partially restricting the passage area through which the gas flows from the inflator into the inflatable jacket. A third drawback of an inflator of this kind resides in the fact that, once the sealing plate of the cap of the gas-containing bottle is perforated, the gas may escape from the inflator by passing through a hole in which the stem of the piercing pin is arranged when said piercing pin is held in the cocked condition against the action of the coil compression spring. Thus, the gas may not flow from the inflator into the inflatable jacket as intended, instead it may escape from the inflator into the surrounding environment without inflating the inflatable jacket. A fourth drawback of an inflator of this kind resides in the fact that it is not possible to adjust the force required for operating the inflator which shall be more or less responsive according to the intended use. Consequently, an inflator of the kind disclosed in the document DE-299 05 908 U exhibits a time of inflation of the inflatable jacket which is too long in duration for the intended application and does not assure a proper and certain inflation of the inflatable protective jacket. In the case of an inflator for inflating a pneumatic protective gear, the time of inflation is a critical parameter for evaluating the effectiveness of the inflator. The time of the inflation is defined herein as the sum of the time required to pierce the gas-containing bottle and the time required by the gas to escape from the bottle. The perforation time is defined as the interval between the instant the blocking device of the inflator is released and the instant the piercing pin of the inflator penetrates the cap of the gas-containing bottle. The escape time of the gas is defined as the interval between the instant the cap of the gas-containing bottle is perforated and the instant the gas-containing bottle is completely emptied. The escape time of the gas is much longer in duration than the perforation time, so that the time of inflation nearly corresponds to the escape time of the gas. In an inflator according to the document DE-299 05 908 U cited above the escape time of the gas is long in duration because: i) the hole made in the cap of gas-containing bottle is small in size, and thus the flow rate of the gas is limited; ii) the passage area for the gas around the piercing pin of the inflator, in the case it is retained in the cap of the gas-containing bottle, is narrow; and iii) the piercing pin of the inflator obstruct the flow of the gas escaping from the gas-containing bottle, even if it does not remain stuck in the sealing cap of the gas-containing bottle. Because of these drawbacks, the gas cannot flow freely and, moreover, a turbulence arises which greatly slows down the outflow speed of the gas. As a result, the escape time of the gas and the time of inflation are too long in duration for the intended use of the inflator. A means for obviating the drawbacks described above would be to make a hole in the cap of the gas-containing bottle having a size as large as possible, consistent with the structure of the cap of the gas-containing bottle, and to completely clear the passage for the gas escaping from the gas-containing bottle.
The International Patent Application No. WO95/33389 describes a safety apparel particularly, but not exclusively, for motorcyclists, equestrians and other unprotected persons comprising inflatable shock-absorbing pads. Inflation of the pads is effected with the aid of a gas-delivering arrangement which includes a gas-containing bottle which is sealed by means of a sealing plate, a small explosive charge, means for detonating the explosive charge in the event of an accident, and further a ball shaped device which is activated by the explosive charge so as to penetrate the sealing plate. The explosive charge is intended to be detonated by means of a striking pin operated by a spring. Means are arranged for storing the energy required therefore in the spring as a result of a relative motion between the wearer of the protective apparel and a motorcycle, a horse or the like caused by an accident. A drawback of the safety apparel described in this document resides in the fact that the apparel is potentially dangerous for the user since it is directly applied to an inflatable protective jacket. Furthermore, such a safety apparel has a rather complicated construction.
Therefore, there is the need to overcome the drawbacks of the known art by providing an inflator for inflating a pneumatic protective article or gear which does not rely on an explosive charge for its operation and is provided with means that permit the piercing pin of the inflator to generate a hole in the sealing cap of the gas-containing bottle having a size as large as possible and to withdraw after it has perforated the sealing cap of the gas-containing bottle, so as to completely clear the passage for the gas escaping from the gas-containing bottle and assure a very short time of inflation of the pneumatic protective article or gear.